Within the everyday work environment, cordless telephones have been found to be extremely useful. However, a conventional cordless telephone in the form of a hand-held handset has been found to be inconvenient in many working conditions because of the need to carry the handset. A cordless telephone instrument in the form of a headset which is worn on the head of the user has been found to be very useful, since both of the user's hands are free to do tasks other than holding the cordless telephone set. One such cordless headset telephone is described in U.S. Pat. No. 4,882,745. This patent discloses a wireless headset telephone whose base station requires a separate analog telephone line or a bridge onto an analog telephone line being used by a role phone station set. The problem with this wireless headset telephone is the need for either utilizing a separate telephone line or requiring an analog telephone line which can be shared with an existing telephone station set. This is a particular disadvantage where the telephone station set is of the electronic variety using either the ISDN digital protocol or a proprietary digital protocol of a switch manufacturer. Most of the business communications systems (also referred to as PBXs) use either the ISDN digital protocol or a proprietary digital protocol unique to that particular manufacturer. In addition, there is a rapid growth in the number of ISDN telephone station sets used by small businesses which are connected to central office switching equipment.
These digital protocols do not allow the base station of the above-referenced patent to be bridged onto a digital link being used by a digital telephone station set. In addition, the costs of providing these digital protocol telephone links is higher than that of an analog link, making it undesirable to have a separate digital link for the wireless headset telephone. Also, there is the problem of having two telephone numbers when a separate digital link is utilized for the wireless headset telephone.
To overcome this problem associated with digital protocol telephone links, it is known in the art to interconnect the base station to the telephone station set by plugging the base station into the telephone station set in place of the handset of the telephone station set. One such wireless headset telephone is Hello Set Model 1341R manufactured by Hello Direct Inc. The problem with this approach is that the user of the headset cannot originate a call or answer an incoming call without physically operating the telephone station set. This is a serious disadvantage, since it restricts the movement of the user with respect to the telephone station set.
One possibility for overcoming the above-mentioned problems would be to design a new telephone station set which allowed for the connection of the base station in such a manner that call origination and call answering could be done from the headset unit itself. The problem with this approach is that electronic telephone station sets are expensive, and owners of these station sets would be reluctant to buy a new station set to obtain the ability to interconnect a cordless headset telephone. In addition, there would have to be a unique base station for each of the proprietary digital protocols. Since the volume of the new telephone station sets would be low relative to the total volume of regular telephone station sets, these new telephone station sets would be expensive.
There exists the need for a cordless headset telephone whose base station can be attached to a standard electronic telephone station set, yet this cordless headset telephone should be able to answer calls and to originate calls remotely from the electronic telephone station set.